1. Field of the Invention
The present invention relates to a road-curve mirror used and a movable body detecting system adapted for transmitting/receiving radio waves between a vehicle and a movable body such as a vehicle or a pedestrian, so that the reception side detects the presence of the transmission side.
2. Description of Background Art
Conventionally, there have been proposed various methods which allow an operated vehicle to detect another movable body such as a vehicle in the neighborhood thereof.
For example, Japanese Patent Laid-open No. Hei2216600 discloses a method, in which a vehicle with an on-board receiver detects the presence of another movable body by receiving, via the on-board receiver, alarm radio waves continuously transmitted from a transmitter mounted on the movable body.
Japanese Patent Laid-open No. Hei7-244800 discloses a method in which an on-board receiver having the basic configuration similar to that of the on-board receiver described as above is improved to decide whether or not the received alarm radio waves are necessary by referring to the operational state of the vehicle and to indicate information based on the necessary alarm radio waves.
When a reception side vehicle is located at a position where the vehicle is hidden from a sight of a transmission side vehicle by an obstacle such as a building, the above alarm radio waves fail to reach the reception side vehicle. In addition, even if the alarm radio waves reaches the reception side vehicle, the strength of the electric field thereof becomes weak to such a degree that the reception side vehicle cannot accurately detect the presence of the transmission side vehicle.
On a road where the visibility of a driver in one vehicle against another vehicle is poor by an obstacle which blocks the presence of another vehicle, a road-curve mirror is generally provided in order that the driver in the vehicle can visually perceive the presence of another vehicle hidden therefrom by the reflection of an image of another vehicle from the mirror. In this case, however, unless the vehicle comes close to the road-curve mirror to some extent, the driver in the vehicle cannot visually detect the presence of another vehicle, or the driver in the vehicle may fail to have a look of the road-curve mirror.
An object of the present invention is to provide a road-curve mirror with a radio wave reflection plate which allows a reception side movable body present at a position where the movable body is hidden from a transmission side movable body to accurately receive movable body detecting radio waves transmitted from the transmission side movable body by making use of a road-curve mirror.
To achieve the above object, according to an embodiment of the present invention, there is provided a road-curve mirror with a radio wave reflection plate for reflecting radio waves wherein the radio waves are transmitted from one movable body and received by another movable body so that the reception side movable body detects the presence of the transmission side movable body. The radio wave reflection plate is mounted in a road-curve mirror provided on such a road that the visibility of a driver in each of the movable bodies against the other is poor.
Since the radio wave reflection plate is provided in the road-curve mirror, movable body detecting radio waves transmitted from a transmission side movable body are reflected from the radio wave reflection plate, reaching a reception side movable body at a difficult to receive position hidden by an obstacle such a building with the electric field strength thereof sufficiently maintained, and are received by the reception side movable body. As a result, the reception side movable body located at the position hidden from the transmission side movable body can accurately detect the presence of the transmission side movable body on the basis of the reception of the movable body detecting radio waves in combination with the detection of an image of the transmission side movable body reflected from the road-curve mirror.
Since the radio wave reflection plate is provided in the road-curve mirror, it does not become an obstacle, that is, it is located at the optimum position.
The radio wave reflection plate is formed by a small-sized, lightweight metal plate or film capable of efficiently reflecting radio waves, and can be compactly disposed in the road-curve mirror. Accordingly, the radio wave reflection plate can be manufactured at a low cost.
According to an embodiment of the present invention, in addition to the configuration of the road-curve mirror with a radio wave reflection plate, the radio wave reflection plate is disposed in a housing provided at the back of a mirror surface portion of the road-curve mirror, and the mirror surface portion of the road-curve mirror is made from a light reflection material allowing transmission of radio waves therethrough.
Since the mirror surface portion of the road-curve mirror is made from a light reflection material which allows transmission of radio waves therethrough and the radio wave reflection plate is disposed at the back of the mirror surface portion of the road-curve mirror, light is reflected from the mirror surface portion, but radio waves pass through the mirror surface portion and are reflected from the radio wave reflection plate to be changed in their traveling direction. As a result, the radio waves thus reflected from the radio wave reflection plate can reach to a reception side movable body at a position hidden from the transmission side movable body with the electric field strength sufficiently maintained, and are accurately received by the reception side movable body.
Since the radio wave reflection plate is disposed in the housing at the back of the mirror surface portion of the road-curve mirror, it can be protected from a natural environmental change such as wind and rain.
This makes it easy to maintain the performance of the radio wave reflection plate. According to an embodiment of the present invention, in addition to the configuration of the road-curve mirror with a radio wave reflection plate, the radio wave reflection plate is supported on a pole for supporting the road-curve mirror in parallel to the road-curve mirror. Since the radio wave reflection plate is supported on the pole of the road-curve mirror, it can be mounted with ease and can additionally be additionally be mounted on the existing road-curve mirror.
According to an embodiment of the present invention, in addition to the configuration of the road-curve mirror with a radio wave reflection plate described in previous embodiments, the reflection plane of the radio wave reflection plate is a concave plane. Since the radio waves reflected from the concave plane of the radio wave reflection plate are collected and are received in an increased electric field strength, it is possible to suppress the transmission output.
According to an embodiment of the present invention, in addition to the configuration of the road-curve mirror with a radio wave reflection plate described in previous embodiments, the reflection plane of the radio wave reflection plate is a convex plane. Since the radio waves reflected from the convex plane of the radio wave reflection plate are extended, it is possible to enlarge the reception range. Such a road-curve mirror with a radio wave reflection plate is therefore suitably used for a wide road having a number of lanes.
Another object of the present invention is to provide a movable body detecting device which allows a reception side movable body present at a position where the movable body is hidden from a transmission side movable body to accurately receive movable body detecting radio waves transmitted from the transmission side movable body.
To achieve the above object, there is provided a movable body detecting device wherein a radio wave relay for relaying the movable body detecting radio waves, are transmitted from one movable body and received by another movable body, so that the reception side movable body detects the presence of the transmission side movable body. The radio wave relay is mounted in a structure provided on such a road wherein the visibility of a driver in each of the movable bodies against the other is poor.
Since the radio wave relay is provided in a structure provided on such a road wherein the visibility of a driver in each of two movable bodies against the other is poor, movable body detecting radio waves transmitted from a transmission side movable body are relayed by the radio wave relay for retransmitting the radio waves to a reception side movable body located at a difficult-to-receive position hidden by an obstacle such as a building, and are accurately received by the reception side movable body. As a result, the reception side movable body located at the position hidden from the transmission side movable body can accurately detect the presence of the transmission side movable body on the basis of the reception of the movable body detecting radio waves.
The construction is exemplified by a road-curve mirror, traffic signal, or a pole such as a telephone pole. In particular, if the radio wave relay is provided in a road-curve mirror, it does not become an obstacle, that is, it is located at the optimum position.
According to an embodiment of the invention, the radio wave relay amplifies and retransmits the movable body detecting radio waves in a specific direction from which the relay receives the movable body detecting radio waves.
With this configuration, even if movable body detecting radio waves transmitted from a transmission side movable body propagate a long-distance to the radio wave relay and thereby the electric field strength thereof is reduced, the radio waves are amplified and retransmitted by the radio wave relay, with a result that the retransmitted radio waves are accurately received by a reception side movable body, even if the reception side movable body is relatively far from the radio wave relay so that the movable body cannot recognize the presence of the transmission side movable body on the basis of an image thereof reflected from a road-curve mirror.
According to the present invention, the radio wave relay adds, to the radio waves to be re-transmitted, a signal indicating that the radio waves have been retransmitted by the relay.
With this configuration, a driver in a reception side movable body can identify whether the received radio wave is the radio wave transmitted directly or by way of the radio wave relay. If receiving the radio waves by way of the relay only, the driver recognizes that the transmission side movable body exists at a position out of the visibility of the driver over an obstacle such as a building; and if receiving the movable body detecting radio waves transmitted directly, the driver recognizes that it is highly possible that the transmission side movable body exists at a position within the visibility of the driver.
According to an embodiment of the present invention, the structure is a road-curve mirror, the radio wave relay is disposed in a housing at the back of a mirror surface portion of the road-curve mirror, and the mirror surface portion of the road-curve mirror is made from a light reflection material allowing transmission of radio waves therethrough.
Since the mirror surface portion of the road-curve mirror is made from a light reflection material and the radio wave relay is disposed at the back of the mirror surface portion of the road-curve mirror, light is reflected from the mirror surface portion, but radio waves pass through the mirror surface portion, being relayed by the radio wave relay, and re-transmitted to be changed in their traveling direction. As a result, the radio waves thus retransmitted from the radio wave relay reach a reception side movable body at a position hidden from the transmission side movable body, and are accurately received by the reception side movable body.
Since the radio wave relay is disposed in the housing at the back of the mirror surface portion of the road-curve mirror, it can be protected from an environmental change in nature such as wind and rain. This makes it easy to maintain the performance of the radio wave relay.
According to an embodiment of the present invention, the structure is a road-curve mirror, and the radio wave relay is supported on a pole for supporting the road-curve mirror in parallel to the road-curve mirror.
Since the radio wave relay is supported on the pole of the road-curve mirror, it can be simply, additionally mounted on the existing road-curve mirror. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.